1. Field of the Invention
The present invention relates to sound analysing apparatus and in particular to apparatus for the analysis of speech.
2. Description of the Prior Art
In connection with the analysis of speech sounds for, for example, the recognition of speech by machines such as computers, many attempts have been made to analyse the formulation of speech. While some work has been done on the mechanics of speech production by, for example, analysing the effects of resonance in the cavities of the vocal tract, other work has concentrated upon the analysis of the waveforms of actual speech.
The present invention is concerned with the latter work. It is well established that voiced sound relies upon the presence of certain basic waveforms which have been referred to as formants and attempts have been made to track these formants in speech passages by frequency filtering and mathematical analysis. In such attempts reliance has been placed upon detecting and tracking the energy content of the speech frequency spectrum. The present apparatus proposes a greatly simplified method and apparatus for formant tracking using a two-dimensional averaging process.